The present invention relates generally to an aluminum base bearing made by powder metallurgy techniques and, more particularly, to a bearing having a surface layer of pre-alloyed aluminum base particles.
It has been known to make aluminum base bearings by powder metallurgy techniques containing a bearing phase of conventional materials such as lead, tin, copper, cadmium, etc. However, considerable difficulty has been experienced in the fabrication and use of such bearings, especially in imparting superior bearing load carrying capacity and anti-seizure properties to the bearing structure. One method used to achieve improved bearing properties was to have a bearing layer in which the particles of the bearing layer are in pre-alloyed powder form, particularly where the bearing phase is in an intra-particle position relative to the aluminum. This bearing with a fine dispersion of the bearing phase in the individual aluminum particles and method of manufacture are described in U.S. Pat. Nos. 3,797,084, and 4,069,369 filed Dec. 18, 1972 and May 4, 1973, respectively, and owned by the assignee of the instant application.
The current trend toward higher output engines, such as turbo charged engines, has given rise to the need for even higher performance bearing materials. Presently, the only bearing materials which consistently meet the performance requirement of these higher output engines are overlay plated tri-metal bearings. These bearings while having good performance characteristics are expensive to produce, exhibit accelerated wear and provide clearance control problems.
Accordingly, it is a principal object of this invention to provide a method of making an aluminum based bearing by powder metallurgy techniques which has improved bearing load carrying capacity and anti-seizure properties.